1. Field of the Invention
This invention relates to a metal seal and an attachment method for the same and a tight-seal construction.
2. Description of the Related Art
Conventionally, various materials such as rubber, resin, etc. have been used to make a seal for a fixation flange for vacuum, inner pressure, and outer pressure. Especially, a metal seal is often used under severe conditions such as high vacuum, high pressure (inner pressure and outer pressure), high temperature, low temperature, and application to corrosive fluids.
However, this metal seal has problems below. That is to say, a conventional metal seal has generally high fastening force, thickness of the flange as an application member (seal attachment member) must be increased, and weight and volume (space for installment) of the apparatus is increased thereby. And, in a conventional metal seal 31 shown in FIG. 4, local plastic deformation is generated on the metal seal 31 disposed between a pair of flat faces 32 and 33 parallel to each other by pressing seal portions K1 and K2, the flat faces 32 and 33, namely, application members 34 and 35 such as flanges are damaged, and reuse of the application members 34 and 35 such as flanges becomes problematic. Naturally, high cost and long time are required to disassemble the apparatus for maintenance and checkup.
The conventional metal seal 31 as shown in FIG. 4, partially and plastically deformed on the pressing seal portions K1 and K2, damages the flat faces 32 and 33 because the metal seal 31 is hardly deformed elastically for high rigidity and receiving fastening force (in the mutual closing directions of the flat faces 32 and 33) directly.
It is therefore an object of the present invention to provide a metal seal easily and economically made, of which fastening force is (despite a metal seal) small and resilient force is large, and thickness of a flange as the application member (attachment member) can be small to contribute to light weight and compactification of the whole apparatus.
And, it is another object of the present invention to provide a metal seal and an attachment method for the metal seal with which the attachment member (application member) of brittle material such as ceramic and soft material such as aluminum can be used for a long time without being damaged, and to provide a metal seal with which stable sealability is always demonstrated without dispersion even when tolerance of depth dimension of sealing groove is high, range of set height within the seal is used is wide, and the seal is easily attached.
Further, it is another object of the present invention to provide a metal seal with which fluid leakage such as blowby is effectively prevented when high pressure works.